DLA and carers allowance is not counted as income when accessing housing benefit . My wife gets DLA middle rate care, higher rate mobility I get carers allowance , we still get full housing and council tax benefit.
If your eldest daughter is still in full time education, university, you should get tax credit for her as well.
This can be quite complicated spicially with your disability benefits, I strongly reccomend you ask your local CAB to do a check that you are getting everything that you should be getting . The CAB are really good for this and know the system inside out.